Presently, timber is often harvested by a system of clear cutting an area of a forest. Because of its advantageous biological and economical characteristics, clear cutting will probably continue to be used as a harvesting method for the foreseeable future. However, since an area which has been clear cut is typically exposed to a great deal of light, growth of sprouts from the roots or stumps of certain types of felled trees, forming a thicket, will occur. Such thickets are usually created when root-sprouting and coppice creating broadleaf deciduous trees are felled.
Small trees in a thicket can cause a great deal of damage to conifer seedlings, since small trees in the thicket compete with the conifer seedlings for available nourishment and light. Aspen is the most troublesome thicket producing tree, due to its high rate of regeneration Also, a fungus known as melampsora pinitorqua, which attacks both aspen leaves and pine seedlings, may be transmitted from small aspen trees in a thicket to pine seedlings, causing great damage to conifer plantations.
In previous years, thicket growth has been controlled by spraying herbicides from the air or by hand to kill thickets originating from felled deciduous trees. Presently, however, due to environmental concerns, spraying of herbicides from the air is no longer allowed. Also, manual spraying of herbicide tends to expose individuals to the herbicide. Therefore, it is preferable to control thicket growth in another way.
Heretofore, the only solution to this problem was to let the thicket grow and then remove it with bush saws, a method which is costly and necessitates the use of much manpower.